2 * EFI Variables - efivars.c
4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
7 * This code takes all variables accessible from EFI runtime and
8 * exports them via sysfs
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 * 17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
27 * remove check for efi_enabled in exit
30 * 26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
33 * 21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
34 * converted driver to export variable information via sysfs
35 * and moved to drivers/firmware directory
36 * bumped revision number to v0.07 to reflect conversion & move
38 * 10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
39 * fix locking per Peter Chubb's findings
41 * 25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
42 * move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
44 * 12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
45 * use list_for_each_safe when deleting vars.
46 * remove ifdef CONFIG_SMP around include <linux/smp.h>
47 * v0.04 release to linux-ia64@linuxia64.org
49 * 20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
50 * Moved vars from /proc/efi to /proc/efi/vars, and made
51 * efi.c own the /proc/efi directory.
52 * v0.03 release to linux-ia64@linuxia64.org
54 * 26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
55 * At the request of Stephane, moved ownership of /proc/efi
56 * to efi.c, and now efivars lives under /proc/efi/vars.
58 * 12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
59 * Feedback received from Stephane Eranian incorporated.
60 * efivar_write() checks copy_from_user() return value.
61 * efivar_read/write() returns proper errno.
62 * v0.02 release to linux-ia64@linuxia64.org
64 * 26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
65 * v0.01 release to linux-ia64@linuxia64.org
68 #include <linux/capability.h>
69 #include <linux/types.h>
70 #include <linux/errno.h>
71 #include <linux/init.h>
73 #include <linux/module.h>
74 #include <linux/string.h>
75 #include <linux/smp.h>
76 #include <linux/efi.h>
77 #include <linux/sysfs.h>
78 #include <linux/kobject.h>
79 #include <linux/device.h>
81 #include <asm/uaccess.h>
83 #define EFIVARS_VERSION "0.08"
84 #define EFIVARS_DATE "2004-May-17"
86 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
87 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
88 MODULE_LICENSE("GPL");
89 MODULE_VERSION(EFIVARS_VERSION);
92 * efivars_lock protects two things:
93 * 1) efivar_list - adds, removals, reads, writes
94 * 2) efi.[gs]et_variable() calls.
95 * It must not be held when creating sysfs entries or calling kmalloc.
96 * efi.get_next_variable() is only called from efivars_init(),
97 * which is protected by the BKL, so that path is safe.
99 static DEFINE_SPINLOCK(efivars_lock);
100 static LIST_HEAD(efivar_list);
103 * The maximum size of VariableName + Data = 1024
104 * Therefore, it's reasonable to save that much
105 * space in each part of the structure,
106 * and we use a page for reading/writing.
109 struct efi_variable {
110 efi_char16_t VariableName[1024/sizeof(efi_char16_t)];
111 efi_guid_t VendorGuid;
112 unsigned long DataSize;
116 } __attribute__((packed));
119 struct efivar_entry {
120 struct efi_variable var;
121 struct list_head list;
125 struct efivar_attribute {
126 struct attribute attr;
127 ssize_t (*show) (struct efivar_entry *entry, char *buf);
128 ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
132 #define EFI_ATTR(_name, _mode, _show, _store) \
133 struct subsys_attribute efi_attr_##_name = { \
134 .attr = {.name = __stringify(_name), .mode = _mode}, \
139 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
140 struct efivar_attribute efivar_attr_##_name = { \
141 .attr = {.name = __stringify(_name), .mode = _mode}, \
146 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
147 #define to_efivar_entry(obj) container_of(obj, struct efivar_entry, kobj)
150 * Prototype for sysfs creation function
153 efivar_create_sysfs_entry(unsigned long variable_name_size,
154 efi_char16_t *variable_name,
155 efi_guid_t *vendor_guid);
157 /* Return the number of unicode characters in data */
159 utf8_strlen(efi_char16_t *data, unsigned long maxlength)
161 unsigned long length = 0;
163 while (*data++ != 0 && length < maxlength)
169 * Return the number of bytes is the length of this string
170 * Note: this is NOT the same as the number of unicode characters
172 static inline unsigned long
173 utf8_strsize(efi_char16_t *data, unsigned long maxlength)
175 return utf8_strlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
179 get_var_data(struct efi_variable *var)
183 spin_lock(&efivars_lock);
184 var->DataSize = 1024;
185 status = efi.get_variable(var->VariableName,
190 spin_unlock(&efivars_lock);
191 if (status != EFI_SUCCESS) {
192 printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
199 efivar_guid_read(struct efivar_entry *entry, char *buf)
201 struct efi_variable *var = &entry->var;
207 efi_guid_unparse(&var->VendorGuid, str);
209 str += sprintf(str, "\n");
215 efivar_attr_read(struct efivar_entry *entry, char *buf)
217 struct efi_variable *var = &entry->var;
224 status = get_var_data(var);
225 if (status != EFI_SUCCESS)
228 if (var->Attributes & 0x1)
229 str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
230 if (var->Attributes & 0x2)
231 str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
232 if (var->Attributes & 0x4)
233 str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
238 efivar_size_read(struct efivar_entry *entry, char *buf)
240 struct efi_variable *var = &entry->var;
247 status = get_var_data(var);
248 if (status != EFI_SUCCESS)
251 str += sprintf(str, "0x%lx\n", var->DataSize);
256 efivar_data_read(struct efivar_entry *entry, char *buf)
258 struct efi_variable *var = &entry->var;
264 status = get_var_data(var);
265 if (status != EFI_SUCCESS)
268 memcpy(buf, var->Data, var->DataSize);
269 return var->DataSize;
272 * We allow each variable to be edited via rewriting the
273 * entire efi variable structure.
276 efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
278 struct efi_variable *new_var, *var = &entry->var;
279 efi_status_t status = EFI_NOT_FOUND;
281 if (count != sizeof(struct efi_variable))
284 new_var = (struct efi_variable *)buf;
286 * If only updating the variable data, then the name
287 * and guid should remain the same
289 if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
290 efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
291 printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
295 if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
296 printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
300 spin_lock(&efivars_lock);
301 status = efi.set_variable(new_var->VariableName,
302 &new_var->VendorGuid,
307 spin_unlock(&efivars_lock);
309 if (status != EFI_SUCCESS) {
310 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
315 memcpy(&entry->var, new_var, count);
320 efivar_show_raw(struct efivar_entry *entry, char *buf)
322 struct efi_variable *var = &entry->var;
328 status = get_var_data(var);
329 if (status != EFI_SUCCESS)
332 memcpy(buf, var, sizeof(*var));
337 * Generic read/write functions that call the specific functions of
340 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
343 struct efivar_entry *var = to_efivar_entry(kobj);
344 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
347 if (!capable(CAP_SYS_ADMIN))
350 if (efivar_attr->show) {
351 ret = efivar_attr->show(var, buf);
356 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
357 const char *buf, size_t count)
359 struct efivar_entry *var = to_efivar_entry(kobj);
360 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
363 if (!capable(CAP_SYS_ADMIN))
366 if (efivar_attr->store)
367 ret = efivar_attr->store(var, buf, count);
372 static struct sysfs_ops efivar_attr_ops = {
373 .show = efivar_attr_show,
374 .store = efivar_attr_store,
377 static void efivar_release(struct kobject *kobj)
379 struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
383 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
384 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
385 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
386 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
387 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
389 static struct attribute *def_attrs[] = {
390 &efivar_attr_guid.attr,
391 &efivar_attr_size.attr,
392 &efivar_attr_attributes.attr,
393 &efivar_attr_data.attr,
394 &efivar_attr_raw_var.attr,
398 static struct kobj_type efivar_ktype = {
399 .release = efivar_release,
400 .sysfs_ops = &efivar_attr_ops,
401 .default_attrs = def_attrs,
405 efivar_unregister(struct efivar_entry *var)
407 kobject_unregister(&var->kobj);
411 static ssize_t efivar_create(struct kobject *kobj,
412 struct bin_attribute *bin_attr,
413 char *buf, loff_t pos, size_t count)
415 struct efi_variable *new_var = (struct efi_variable *)buf;
416 struct efivar_entry *search_efivar, *n;
417 unsigned long strsize1, strsize2;
418 efi_status_t status = EFI_NOT_FOUND;
421 if (!capable(CAP_SYS_ADMIN))
424 spin_lock(&efivars_lock);
427 * Does this variable already exist?
429 list_for_each_entry_safe(search_efivar, n, &efivar_list, list) {
430 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
431 strsize2 = utf8_strsize(new_var->VariableName, 1024);
432 if (strsize1 == strsize2 &&
433 !memcmp(&(search_efivar->var.VariableName),
434 new_var->VariableName, strsize1) &&
435 !efi_guidcmp(search_efivar->var.VendorGuid,
436 new_var->VendorGuid)) {
442 spin_unlock(&efivars_lock);
446 /* now *really* create the variable via EFI */
447 status = efi.set_variable(new_var->VariableName,
448 &new_var->VendorGuid,
453 if (status != EFI_SUCCESS) {
454 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
456 spin_unlock(&efivars_lock);
459 spin_unlock(&efivars_lock);
461 /* Create the entry in sysfs. Locking is not required here */
462 status = efivar_create_sysfs_entry(utf8_strsize(new_var->VariableName,
463 1024), new_var->VariableName, &new_var->VendorGuid);
465 printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
470 static ssize_t efivar_delete(struct kobject *kobj,
471 struct bin_attribute *bin_attr,
472 char *buf, loff_t pos, size_t count)
474 struct efi_variable *del_var = (struct efi_variable *)buf;
475 struct efivar_entry *search_efivar, *n;
476 unsigned long strsize1, strsize2;
477 efi_status_t status = EFI_NOT_FOUND;
480 if (!capable(CAP_SYS_ADMIN))
483 spin_lock(&efivars_lock);
486 * Does this variable already exist?
488 list_for_each_entry_safe(search_efivar, n, &efivar_list, list) {
489 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
490 strsize2 = utf8_strsize(del_var->VariableName, 1024);
491 if (strsize1 == strsize2 &&
492 !memcmp(&(search_efivar->var.VariableName),
493 del_var->VariableName, strsize1) &&
494 !efi_guidcmp(search_efivar->var.VendorGuid,
495 del_var->VendorGuid)) {
501 spin_unlock(&efivars_lock);
504 /* force the Attributes/DataSize to 0 to ensure deletion */
505 del_var->Attributes = 0;
506 del_var->DataSize = 0;
508 status = efi.set_variable(del_var->VariableName,
509 &del_var->VendorGuid,
514 if (status != EFI_SUCCESS) {
515 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
517 spin_unlock(&efivars_lock);
520 list_del(&search_efivar->list);
521 /* We need to release this lock before unregistering. */
522 spin_unlock(&efivars_lock);
523 efivar_unregister(search_efivar);
525 /* It's dead Jim.... */
529 static struct bin_attribute var_subsys_attr_new_var = {
530 .attr = {.name = "new_var", .mode = 0200},
531 .write = efivar_create,
534 static struct bin_attribute var_subsys_attr_del_var = {
535 .attr = {.name = "del_var", .mode = 0200},
536 .write = efivar_delete,
540 * Let's not leave out systab information that snuck into
544 systab_read(struct kset *kset, char *buf)
551 if (efi.mps != EFI_INVALID_TABLE_ADDR)
552 str += sprintf(str, "MPS=0x%lx\n", efi.mps);
553 if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
554 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
555 if (efi.acpi != EFI_INVALID_TABLE_ADDR)
556 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
557 if (efi.smbios != EFI_INVALID_TABLE_ADDR)
558 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
559 if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
560 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
561 if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
562 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
563 if (efi.uga != EFI_INVALID_TABLE_ADDR)
564 str += sprintf(str, "UGA=0x%lx\n", efi.uga);
569 static EFI_ATTR(systab, 0400, systab_read, NULL);
571 static struct subsys_attribute *efi_subsys_attrs[] = {
573 NULL, /* maybe more in the future? */
576 static decl_subsys(vars, NULL);
577 static decl_subsys(efi, NULL);
580 * efivar_create_sysfs_entry()
582 * variable_name_size = number of bytes required to hold
583 * variable_name (not counting the NULL
584 * character at the end.
585 * efivars_lock is not held on entry or exit.
586 * Returns 1 on failure, 0 on success
589 efivar_create_sysfs_entry(unsigned long variable_name_size,
590 efi_char16_t *variable_name,
591 efi_guid_t *vendor_guid)
593 int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
595 struct efivar_entry *new_efivar;
597 short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
598 new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
600 if (!short_name || !new_efivar) {
606 memcpy(new_efivar->var.VariableName, variable_name,
608 memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
610 /* Convert Unicode to normal chars (assume top bits are 0),
612 for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
613 short_name[i] = variable_name[i] & 0xFF;
615 /* This is ugly, but necessary to separate one vendor's
616 private variables from another's. */
618 *(short_name + strlen(short_name)) = '-';
619 efi_guid_unparse(vendor_guid, short_name + strlen(short_name));
621 kobject_set_name(&new_efivar->kobj, "%s", short_name);
622 new_efivar->kobj.kset = &vars_subsys;
623 new_efivar->kobj.ktype = &efivar_ktype;
624 i = kobject_register(&new_efivar->kobj);
634 spin_lock(&efivars_lock);
635 list_add(&new_efivar->list, &efivar_list);
636 spin_unlock(&efivars_lock);
641 * For now we register the efi subsystem with the firmware subsystem
642 * and the vars subsystem with the efi subsystem. In the future, it
643 * might make sense to split off the efi subsystem into its own
644 * driver, but for now only efivars will register with it, so just
651 efi_status_t status = EFI_NOT_FOUND;
652 efi_guid_t vendor_guid;
653 efi_char16_t *variable_name;
654 struct subsys_attribute *attr;
655 unsigned long variable_name_size = 1024;
661 variable_name = kzalloc(variable_name_size, GFP_KERNEL);
662 if (!variable_name) {
663 printk(KERN_ERR "efivars: Memory allocation failed.\n");
667 printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
671 * For now we'll register the efi subsys within this driver
674 error = firmware_register(&efi_subsys);
677 printk(KERN_ERR "efivars: Firmware registration failed with error %d.\n", error);
681 vars_subsys.kobj.kset = &efi_subsys;
683 error = subsystem_register(&vars_subsys);
686 printk(KERN_ERR "efivars: Subsystem registration failed with error %d.\n", error);
687 goto out_firmware_unregister;
691 * Per EFI spec, the maximum storage allocated for both
692 * the variable name and variable data is 1024 bytes.
696 variable_name_size = 1024;
698 status = efi.get_next_variable(&variable_name_size,
703 efivar_create_sysfs_entry(variable_name_size,
710 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
712 status = EFI_NOT_FOUND;
715 } while (status != EFI_NOT_FOUND);
718 * Now add attributes to allow creation of new vars
719 * and deletion of existing ones...
721 error = sysfs_create_bin_file(&vars_subsys.kobj,
722 &var_subsys_attr_new_var);
724 printk(KERN_ERR "efivars: unable to create new_var sysfs file"
725 " due to error %d\n", error);
726 error = sysfs_create_bin_file(&vars_subsys.kobj,
727 &var_subsys_attr_del_var);
729 printk(KERN_ERR "efivars: unable to create del_var sysfs file"
730 " due to error %d\n", error);
732 /* Don't forget the systab entry */
734 for (i = 0; (attr = efi_subsys_attrs[i]) && !error; i++) {
736 error = subsys_create_file(&efi_subsys, attr);
740 printk(KERN_ERR "efivars: Sysfs attribute export failed with error %d.\n", error);
744 subsystem_unregister(&vars_subsys);
746 out_firmware_unregister:
747 firmware_unregister(&efi_subsys);
750 kfree(variable_name);
758 struct efivar_entry *entry, *n;
760 list_for_each_entry_safe(entry, n, &efivar_list, list) {
761 spin_lock(&efivars_lock);
762 list_del(&entry->list);
763 spin_unlock(&efivars_lock);
764 efivar_unregister(entry);
767 subsystem_unregister(&vars_subsys);
768 firmware_unregister(&efi_subsys);
771 module_init(efivars_init);
772 module_exit(efivars_exit);